Sodium/phosphate cotransporter

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Solute carrier family 34 (type II sodium/phosphate cotransporter), member 1
Symbols SLC34A1 ; FRTS2; NAPI-3; NPHLOP1; NPT2; NPTIIa; SLC11; SLC17A2
External IDs OMIM182309 HomoloGene20663 GeneCards: SLC34A1 Gene
Species Human Mouse
Entrez 6569 20505
Ensembl ENSG00000131183 ENSMUSG00000021490
UniProt Q06495 n/a
RefSeq (mRNA) NM_001167579 NM_011392
RefSeq (protein) NP_001161051 NP_035522
Location (UCSC) Chr 5:
177.38 – 177.4 Mb
Chr 13:
55.4 – 55.41 Mb
PubMed search [1] [2]

Sodium/phosphate cotransporter also known as Na+-Pi cotransport (NaPi-2a) or solute carrier family 34, member 1 (SLC34A1) is a protein in humans that is encoded by the SLC34A1 gene.[1] This gene encodes a member of the type II sodium-phosphate cotransporter family.


The sodium/phosphate cotransporter is a protein found in the proximal tubule of the nephron. It is responsible for reabsorbing approximately 80% of the phosphate that has been filtered out at the glomerulus. The transporter moves hydrogen phosphate (HPO42−) into the cell along with 3 sodium ions. Alternatively it can move dihydrogen phosphate (H2PO4 along with 2 sodium ions. For both movements the net charge is +1. Once inside the cell hydrogen phosphate and dihydrogen phosphate may react with water to form each other. Transport of these chemicals out of the cell at the basolateral surface is not understood currently.[2]

The NaPi channels are regulated by parathyroid hormone (PTH). PTH acts to decrease phosphate reabsorption from the renal filtrate and therefore promote its excretion into the urine. It does this by causing for endocytosis of NaPi transporters on the apical surface of the cell. With less transporter available more phosphate is lost in the urine.[2]

Clinical significance[edit]

Mutations in this gene are associated with hypophosphatemia nephrolithiasis/osteoporosis 1.[1]

See also[edit]


  1. ^ a b "Entrez Gene: Solute carrier family 34 (sodium phosphate), member 1". 
  2. ^ a b Boron WF, Boulpaep EL (2012). Medical Physiology: a cellular and molecular approach (2 ed.). Philadelphia: Saunders. ISBN 1-4377-1753-5. 

Further reading[edit]

  • Tenenhouse H (1999). "X-linked hypophosphataemia: a homologous disorder in humans and mice.". Nephrol Dial Transplant 14 (2): 333–41. doi:10.1093/ndt/14.2.333. PMID 10069185. 

External links[edit]